Still fighting vibration, need more help!

[pdqwrx]

So, I replaced the center bearing on the drive shaft last night and found the old one to be loose and very sagged. After replacement I still have the vibration so I am thinking that perhaps it is not the drive shaft. I checked the joints and there was a small amount of "Notchyness" to them but my mechanic who was lending me the lift says that the drive line seemed to be in pretty great shape except for the center bearing. Today I went on a 200 mile drive and really paid attention to what was going on and found some interesting data now that the vibration is bad enough to always feel it.1) It's nature seems to change- Sometimes it's from 35 to 45 mph and sometimes it is from 30 to 50 mph.

2) Under hard breaking I can now feel it in the steering wheel and it gets worse in the steering wheel between 50-30 mph.

3) Has anyone (Including Q45tech) actually seen a warped hub?

I borrowrd an run out tool to measure it tomorrow.

Looking for any suggestions because this NVH sucks arse!!!!!!!!!

ThanksScott

[Q45tech]

What is radial force variation number for each tire wheel combination?

Should be under 10 pounds, 5 is better. Cold and Hot

Seen lots and lots of out of spec wheels like 75% on older cars. After market are worse!

Vibrations that change have some component that heats up: Tires, wheels, rotors............what is as mounted rotor with 5 lugs hold it on vs wheel radial and axial runout............less than 0.0028" cold and hot?

[DrewQ45]

At 35 - 40 Mph, (when vibration is strongest), put the car in neutral and see if vibration goes away. If it does, you may have a torque converter issue. More than likely though, you do have a drive-shaft issue. I have one too and the speeds you described are right in line. The hard-braking vibe that you feel in the steering are of a different nature, and, would be due to warped rotors on the front. Try having them skimmed or change to new rotors.

I'm waiting patiently until I can get my hands on a 94-95 drive-shaft. Everyone says buy new but I'm not up to laying out 800 right now and don't mind experimenting a bit. My problems started with my driveshaft being disconnected improperly during a transmission replacement.

[elwesso]

first step is to make sure its in the drivetrain... jack the back end of the car up and see if the vibration is there.

[pdqwrx]

OK, what is radial force variation ? If you can explain it to me I will check for it....I just had the front rotors turned so either the machine that turned them was out of whack (Possible) or I bolted them to a warped or wobbly hub.

I have ran the car at speeds while on the lift and could not see or feel the vibration. So perhaps it only does it under load.

The vibration goes away when you let off the gas.

I am doing more looking today....

Thanks for everyones help.Scott

[elwesso]

OK, what is radial force variation ? If you can explain it to me I will check for it....I just had the front rotors turned so either the machine that turned them was out of whack (Possible) or I bolted them to a warped or wobbly hub.

I have ran the car at speeds while on the lift and could not see or feel the vibration. So perhaps it only does it under load.

The vibration goes away when you let off the gas.

I am doing more looking today....

Thanks for everyones help.Scott

Im iffy... with driveshaft related vibrations, in my expereince, will only get WORSE when you lift the wheels up...... Because theresnothing loaded to sort of prevent the vibration.....

At this point, I am inclined to want to eliminate the driveshaft.... Its something that we can come back to if we have to, but I kinda iffy..... The alignment on the drivesahft doesnt change...

Im wondinerg if like the differential bushigns are bad, or maybe the subframe is moving out of alignment?

[96Qowner]

OK, what is radial force variation ? If you can explain it to me I will check for it....

"Radial force variation is the amount of change in stiffness of the sidewall and footprint when a load is placed against the tire."

http://www.gsp9700.com/pub/tec...t.cfm

Wheel/tire balance can be dynamic, rather than static, as one might think. I suffered vibration with my Accord for years before my thick head understood that tires don't always stay round, for instance. And go figure, wheels don't stay round either. You can balance them all you want, but they just aren't round.

Find a shop with a Hunter GSP9700 (they have an online locator) and have them do a RoadForce evaluation for you. Kinda spendy, but worth it, just to know, IMO.

[elwesso]

Most chain tire places like discount tire and such have the appropriate balacing machines..... The Hunter 9700 is the industry standard among tire places that sell expensive tires.... Ma and Pa may not have a hunter 9700, however all you have to do is ask.....

The thing that concerns me is that it goes away under decelleration (or letting off the gas)... thats not characteristic of tires.

What about a wheel bearing?? htat would certainly make sense, kinda.

[96Qowner]

Found another old post by Dennis:

"By now hopefully members know 30-40 mph vibration = driveshaftand 55-65 mph = tires wheel balance [and warped rotors] and a steady increasing vibration with peaks at 55-65 and 110-130 = tires that have too much radial force variations.

Vibrations that change with temperature, get better as tires warm up at same speed is a radial force problem."

zerothread?id=58982

I'm thinking pdgwrx has two issues - got a bad wheel/tire combo somewhere.

[elwesso]

thanks for bringing that up... After I put my summer wheels back on and hawk pads, ill get the rotors trued...

[pdqwrx]

I just checked runout on drivers side and it measures .002" with both the new rotor and the hub......Is this in spec?Scott

[96Qowner]

According to Dennis:

"Important to determine whether the hubs or the brand new rotor is at fault.Since you are trying for 0.001" at the rotor outer edge."

"Luckily the extra volume of lines and ABS system isolates the brake pedal so mild warping is damped and it has to get bad >0.003 before an experienced driver feels it . I have trued rotors that were warped 10 times more than that before some [totally numb] drivers noticed. Made my partial jump out of my mouth on each application."

zerothread?id=152992

Looks like you're pretty close though:

"0.0028" TOTAL movement of the gauge.

The problem is that the inside always warps more than the outside, so not a test unless used to precision mount [select holes to studs] the rotor after a precision trueing.0.001" would be better and is possible if the hubs and inside hats are clean............I even grind my hubs!"

zerothread?id=47476

Lots of good info on a search of runout, posts by Q45tech.

Sheesh, I took the time to scan through that entire second thread. Tangalora ... amazing ... absolutely amazing ... there won't be another one like her. Whew!
Modified by 96Qowner at 1:05 PM 3/30/2006

[pdqwrx]

I just read part of my post from earlier and I didn't get one detail right....The vibration stays the same regardless of throttle. I can be accelerating or deceleratoring and still feel it. I also feel it with the transmission in neutral. That is what I meant to say.....Well i just mounted one new rotor and am about to mount the other (I went with the Cryo treated power slots) and then a test drive.

Now, my tire guy rotated the tires front to back and remounted the tires that WERE on the front (On back now) inside out to help with a camber related tire wera issue up front. And the vibration stayed exactly the same. I have turned the rotors and the vibration is exactly the same. I replaced the center bearing on the drive shaft and the vibration is exactly the same...... I am starting to see a trend here! perhaps I should look at the transmission?

Most chain tire places like discount tire and such have the appropriate balacing machines..... The Hunter 9700 is the industry standard among tire places that sell expensive tires.... Ma and Pa may not have a hunter 9700, however all you have to do is ask.....

The thing that concerns me is that it goes away under decelleration (or letting off the gas)... thats not characteristic of tires.

What about a wheel bearing?? htat would certainly make sense, kinda.

)

[pdqwrx]

So the new pads are in and the brake induced vibration is GONE- For now.......But the chasis vibration is still there.........So I doubt it is warped hubs.

[1996q45]

I had the same vibration problems with my 1996 Q45. I have fixed all vibrations. My driveshaft center bearing was sagging and the u joints were notchy. I replaced the driveshaft. It took me a while also to realize the previous owner had removed the spaces between the center bearing and frame to make up the difference because the center bearing was sagging. I added washers until the vibration went away. The next problem was the transmission mount sagged and touched the frame. The engine mounts need to be replaced because they also sag and transfer vibration to the frame. One of the silicon filled bushings in the rear subframe had failed. I could also see where the subframe was touch the body because of the failed bushing. The front lower tie rod bushing leaked silicon which caused the steering wheel to shake and the car would always goto the right. I had to fix everything myself and now the car drives like it is brand new. The only problem I have is the torque converter does not always disengage when I downshift. You can't rely on the dealership to fix the problems. My car had a warrenty on it and the dealership did not find anything wrong when the vibrations first appeared. I recommend buying from drivewire. The parts are OEM and half the cost of the dealership.

[JedCoop]

I have ran the car at speeds while on the lift and could not see or feel the vibration. So perhaps it only does it under load.

The vibration goes away when you let off the gas.

This sounds like a common U-joint problem in older cars. I went through a lot of U-joints in my '69 Camaro. When they started going bad the vibration was only at certain power levels, or as you let off or put on the power.

In the Q that means a new driveshaft unless... but then again, there was no center bearing in those cars. I can see that extra torque might cause play in the center bearing to get worse. However I really have no experience with it, I just know it costs about $100 for the part.

[DrewQ45]

I just read part of my post from earlier and I didn't get one detail right....The vibration stays the same regardless of throttle. I can be accelerating or deceleratoring and still feel it. I also feel it with the transmission in neutral. That is what I meant to say.....Well i just mounted one new rotor and am about to mount the other (I went with the Cryo treated power slots) and then a test drive.

Now, my tire guy rotated the tires front to back and remounted the tires that WERE on the front (On back now) inside out to help with a camber related tire wera issue up front. And the vibration stayed exactly the same. I have turned the rotors and the vibration is exactly the same. I replaced the center bearing on the drive shaft and the vibration is exactly the same...... I am starting to see a trend here! perhaps I should look at the transmission?

)

I'd still say drive shaft. When you neutralled it, it should have made a difference if transmission related.

When diagnosing mine, I ran the car on a lift which right away, elimingates the front end. Soon as it reached 35-40 Mph the vibration started. Neutralled the transmission and no difference. I even REMOVED both rear wheels and the vibe stayed with no variation whatsoever.

I did it just for kicks because I know exactly when my problem started occuring. It happened right after my transmission replacement and my mechanic admiited to pulling the shaft at the guibos (rubber donut) which shouldnt have been done.